Microbial Diversity – Vocabulary Flashcards

100 vocabulary flashcards summarizing key terms and definitions from the lecture on microbial diversity.

The vast variety of cellular and acellular microorganisms that inhabit virtually every environment on Earth.

Microbial Diversity

A unicellular organism lacking a membrane-bound nucleus or organelles; includes Bacteria and Archaea.

Prokaryote

Any cell or organism with a true, membrane-bound nucleus and organelles; includes animals, plants, fungi, protozoa, and algae.

Eukaryote

Tiny, single-celled prokaryotes that occur in almost all habitats and display great structural and metabolic diversity.

Bacteria

A domain of prokaryotes distinct from bacteria, often inhabiting extreme environments but also common in soils, oceans, and the human body.

Archaea

Autotrophic, oxygen-producing, gram-negative prokaryotes often called blue-green algae.

Cyanobacteria

Heterotrophic eukaryotes such as yeasts, molds, and mushrooms that absorb nutrients and act as principal decomposers.

Fungi

Single-celled, usually motile eukaryotes that feed on organic matter and may be free-living or parasitic.

Protozoa

Photosynthetic, chlorophyll-containing eukaryotes found in water, soils, and even snow.

Algae

A submicroscopic infectious agent that replicates only inside living cells of organisms.

Virus

A small, circular single-stranded RNA pathogen that infects plants.

Viroid

A misfolded protein that induces abnormal folding in normal proteins, causing fatal neurodegenerative diseases.

Prion

Microbes composed of cells, including prokaryotes (bacteria, cyanobacteria, archaea) and eukaryotes (fungi, protozoa, algae).

Cellular Microorganism

Infectious entities lacking cellular structure, such as viruses, viroids, and prions.

Acellular Agent

A protective outer layer in some bacteria that aids moisture retention and surface adherence.

Capsule

A rigid outer layer that maintains shape and protects bacterial cells.

Cell Wall (Bacteria)

Gel-like interior of a cell containing water, enzymes, salts, organelles, and other molecules.

Cytoplasm

Phospholipid bilayer surrounding the cytoplasm, regulating substance movement in and out of the cell.

Plasma Membrane

Hair-like surface appendages that help bacteria attach to surfaces or other cells.

Pili

Shorter pili specialized for surface adhesion.

Fimbriae

Long, whip-like structures that propel cells through liquid environments.

Flagella

Cellular structure where proteins are synthesized from messenger RNA.

Ribosome

Small, circular, gene-carrying DNA molecule independent of the bacterial chromosome.

Plasmid

Region within a prokaryotic cell that contains the single, looped chromosome.

Nucleoid

Spherical bacterial cells typically 0.5–1.25 µm in diameter.

Cocci

A single spherical bacterium appearing alone.

Micrococcus

Pair of cocci resulting from division in one plane (e.g., Diplococcus pneumoniae).

Diplococcus

Chain of cocci formed by repeated division in one plane.

Streptococcus

Group of four cocci arranged in a square after division in two planes.

Tetracoccus

Cuboidal packet of eight cocci produced by division in three planes.

Sarcina

Cluster of cocci resembling grape bunches due to division in multiple planes.

Staphylococcus

Rod-shaped bacterium typically 0.5–1.2 µm wide and 3–7 µm long.

Bacillus

Single, unattached rod-shaped bacterium.

Monobacillus

Pair of bacilli remaining together after division.

Diplobacillus

Chain of bacilli aligned end-to-end.

Streptobacillus

Side-by-side alignment of bacilli resembling a fence.

Palisade Arrangement

Rigid, helical bacterium with more than one turn of helix, often flagellated.

Spirillum

Comma-shaped, curved rod bacterium with polar flagella (e.g., Vibrio cholerae).

Vibrio

Flexible, corkscrew-shaped bacterium lacking flagella on surface (e.g., Treponema pallidum).

Spirochaete

Rod-shaped cells forming long chains enclosed in a sheath, common in sewage (e.g., Sphaerotilus natans).

Filamentous Bacterium

Bacilli attached by stalks to a surface, radiating like flower petals (e.g., Caulobacter).

Rosette Arrangement

Bacteria with star-like morphology, such as genus Stella.

Star-shaped Bacterium

Flat, square microbial cells found in high-salt environments (e.g., Haloarcula).

Square-shaped Bacterium

Species capable of altering shape or size in response to environmental conditions.

Pleomorphic Bacterium

Microorganism that thrives at high temperatures, around 78 °C.

Thermophile

Microorganism that grows optimally at very low temperatures, down to −19 °C.

Psychrophile

One of the three domains of life, containing true bacteria.

Domain Bacteria

Domain of prokaryotes genetically distinct from bacteria with diverse energy sources.

Domain Archaea

Domain encompassing all organisms with membrane-bound nuclei.

Domain Eukarya

Hypothetical ancestral organism from which Bacteria, Archaea, and Eukarya evolved.

Common Ancestor (Three Domains)

Organism that produces its own organic compounds from inorganic sources.

Autotroph

Organism that obtains carbon and energy by consuming organic molecules.

Heterotroph

Light-driven process that splits water to release oxygen, as in cyanobacteria.

Oxygenic Photosynthesis

Conversion of CO₂ into organic compounds, performed by cyanobacteria and some archaea.

Carbon Fixation

Habitat with conditions such as high heat, salinity, or acidity where extremophiles live.

Extreme Environment

Asexual reproductive process in prokaryotes producing two identical daughter cells.

Binary Fission

Time required for a bacterial population to double; often faster in prokaryotes.

Generation Time

Bacteria with thin peptidoglycan and outer membrane, staining pink in Gram stain (e.g., cyanobacteria).

Gram-Negative

Presence of bacteria in nearly all natural habitats: soil, water, air, and living organisms.

Ubiquitous Distribution

Community of microorganisms, such as E. coli, residing in animal digestive tracts.

Intestinal Microflora

One of the smallest known rod-shaped eubacteria, 0.15–0.3 µm in size.

Dialister pneumosintes

Large filamentous bacterium reaching up to 45 µm in diameter.

Beggiatoa mirabilis

Spiral bacterium associated with stomach ulcers.

Helicobacter pylori

Comma-shaped bacterium that causes cholera.

Vibrio cholerae

Spirochaete responsible for syphilis.

Treponema pallidum

Filamentous bacterium common in sewage and sugar-industry effluents.

Sphaerotilus natans

Iron-depositing filamentous bacterium found in ferrous water.

Leptothrix

Filamentous, partially acid-fast genus found in soil and water.

Nocardia

Stalked bacterium forming rosette clusters attached to substrates.

Caulobacter

Square-shaped, salt-loving archaeon.

Haloarcula

Genus of star-shaped bacteria.

Stella

Protein coat encasing viral genetic material.

Capsid

Complete, infectious virus particle existing outside a host cell.

Virion

Lipid membrane surrounding some viruses, derived from host cell membranes.

Viral Envelope

DNA or RNA molecules encoding viral proteins.

Viral Genome

Layer between capsid and envelope in certain viruses containing proteins that aid infection.

Viral Tegument

First virus discovered (1898) by Martinus Beijerinck, infecting tobacco plants.

Tobacco Mosaic Virus

Spread of viruses via blood-sucking insects or other carriers.

Vector Transmission

Transmission pathway where pathogens in feces reach new hosts via mouth, food, or water.

Faecal–Oral Route

Membrane-bound compartment in eukaryotes that houses chromosomes.

Nucleus

Internal eukaryotic structure surrounded by lipid bilayer, such as mitochondria or Golgi bodies.

Membrane-Bound Organelle

Eukaryotic organelles responsible for aerobic energy production.

Mitochondria

Membranous network for protein (rough ER) and lipid (smooth ER) synthesis in eukaryotes.

Endoplasmic Reticulum

Stacked membranes that modify, sort, and package proteins for secretion.

Golgi Apparatus

Cylindrical eukaryotic structure involved in cell division and cilia formation.

Centriole

Feature of eukaryotic chromosomes allowing DNA replication to start at many specific sites.

Multiple Origins of Replication

Light-absorbing molecule, such as those in cyanobacteria, that captures photons for photosynthesis.

Photopigment

Organism, mainly fungi, that breaks down dead organic matter.

Decomposer

Process where decomposers release elements back into the environment for reuse.

Nutrient Cycling

Dormant, protective form allowing protozoa to survive unfavorable conditions.

Resting Cyst

Protozoan disease of humans caused by Plasmodium species.

Malaria

Intestinal infection caused by the protozoan Entamoeba histolytica.

Amoebiasis

Diarrheal illness due to the protozoan Giardia lamblia.

Giardiasis

Disease caused by the protozoan Toxoplasma gondii, often linked to cats.

Toxoplasmosis

Sexually transmitted infection caused by Trichomonas vaginalis.

Trichomoniasis

Protozoan disease transmitted by sandfly bites, caused by Leishmania species.

Leishmaniasis

Fatal neurodegenerative disease class caused by prions, producing sponge-like brain lesions.

Transmissible Spongiform Encephalopathy (TSE)